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HK: Fachverband Hadronen und Kerne
HK 81: Hadron Structure and Spectroscopy II
HK 81.5: Vortrag
Freitag, 20. März 2009, 12:00–12:15, H-ZO 30
Generalized Parton Distributions in Chiral Perturbation Theory — •Nikolai Kivel, Maxim Polyakov, and Aleksey Vladimirov — Ruhr Universitet, Bochum
We used χPT approach to study the small−t behavior of the Generalized Parton Distributions (GPDs). We demonstrate that in the region of Bjorken xBj∼ mπ2/(4π Fπ)2 and/or xBj∼ |t|/(4π Fπ)2 the standard χPT for the pion GPDs is not sufficient and one must perform all order resummation of χPT. We develop the technique in order to sum the problematic contributions with the leading logarithmic accuracy. We apply this approach for the pion GPDs and compute their behavior at the region of small-xBj. Explicit resummation allows us to reveal novel phenomena – the form of the leading chiral correction to pion PDFs and GPDs depends on the small x asymptotic of the pion PDFs. In particular, if the pion PDF in the chiral limit has the Regge-like small x behaviour q(x)∼ 1/xω, the leading large impact parameter (b⊥→∞) asymptotics of the quark distribution in the transverse plane has the form (mπ=0) q(x,b⊥)∼ 1/xω lnω(b⊥2)/b⊥2(1+ω). This result is model independent and it is controlled completely by the all order resummed χPT.